For over twenty years, McDonald's Corporation, which has well-known restaurants, has used lamp-mounting elongate roof fixtures on the roofs its restaurants as a part of its "signage." Each such roof fixture, at least in the most common form, includes a support having a roof-contact portion and an upper portion which is parallel to and spaced from the roof, a beam over and along the support in position suspended above the roof, and a light source shrouded under the beam.
One version of such roof fixtures, still in wide use, has as its light source either one centered fluorescent tube or a pair of parallel tubes, such tubes being mounted in spaces provided along the support underneath the beam. Light from these tubes is emitted below the lower edge of the beam and onto the roof portions between adjacent to the fixtures. Still another version of such roof fixtures uses what is known as "Light-Pipe" optical system to achieve the same result.
Another McDonald's roof fixture, which is the subject of U.S. Pat. No. 5,081,567 (Weiss), places a lamp inside the roof beam itself adjacent to windows formed on either side of the beam itself. A lamp, which is attached to an end closure plate, is oriented along the beam adjacent to the windows in the beam and projects light through the windows onto the roof, causing strong glare to persons around a building which has such fixtures on the roof.
All of such prior art has significant problems and disadvantages. The purpose of this invention is to overcome such problems and disadvantages.
In addition to the problem of glare, the roof fixture of the Weiss patent has its ballast located at a position remote from the lamp. Such position of the ballast can tend to complicate service in that a serviceperson must be on the roof to deal with the ballast. Furthermore, the orientation of the lamp, in a direction along the beam, is quite inefficient if the purpose is to illuminate the roof surface, inasmuch as the primary directions for light discharge from the lamp are not fully oriented toward the area intended to be lit. And, if the lamp is of the high intensity discharge (HID) type having an arc stream, the generally horizontal orientation of the lamp causes the arc-stream of the lamp to droop toward that part of the lamp which is under the arc stream, which can result in a hot spot significantly shortening lamp life.
While the nature of the lamp used in the Weiss patent causes a higher level of roof illumination than fluorescent lamps provided, or were intended to provide, illumination of the roof surface by the Weiss fixture, with its above-the-beam support and light projecting out windows formed in the sides of the beams, has been observed to be very uneven. And, as already noted, the side glare caused by such windowed configuration is understood to be a problem.
A lamp-mounting elongate roof fixture, with an optical system which provides better intensity and evenness of light on the roof, uses light and energy more efficiently, eliminates glare, and is easier to maintain, would be an important advance.